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  • richardmitnick 9:54 am on November 21, 2014 Permalink | Reply
    Tags: , , , , , NASA/ESA Hubble,   

    From SPACE.com: “Planet Uranus: Facts About Its Name, Moons and Orbit” 

    space-dot-com logo

    SPACE.com

    November 18, 2014
    Charles Q. Choi

    Uranus is the seventh planet from the sun and the first to be discovered by scientists. Although Uranus is visible to the naked eye, it was long mistaken as a star because of the planet’s dimness and slow orbit. The planet is also notable for its dramatic tilt, which causes its axis to point nearly directly at the sun.

    ur

    British astronomer William Herschel discovered Uranus accidentally on March 13, 1781, with his telescope while surveying all stars down to those about 10 times dimmer than can be seen by the naked eye. One “star” seemed different, and within a year Uranus was shown to follow a planetary orbit.

    Uranuswas named after the Greek sky deity Ouranos, the earliest of the lords of the heavens. It is the only planet to be named after a Greek god rather than a Roman one. Before the name was settled on, many names had been proposed for the new planet, including Hypercronius (“above Saturn”), Minerva (the Roman goddess of wisdom), and Herschel, after its discoverer. To flatter King George III of England, Herschel himself offered Georgium Sidus (“The Georgian Planet”) as a name, but that idea was unpopular outside of England and George’s native Hanover. German astronomer Johann Bode, who detailed Uranus’ orbit, gave the planet its ultimate name.

    Physical characteristics

    Uranusis blue-green in color, the result of methane in its mostly hydrogen-helium atmosphere. The planet is often dubbed an ice giant, since 80 percent or more of its mass is made up of a fluid mix of water, methane, and ammonia ices.

    Unlike the other planets of the solar system, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star. This unusual orientation might be due to a collision with a planet-size body, or several small bodies, soon after it was formed.

    This unusual tilt gives rise to extreme seasons roughly 20 years long, meaning that for nearly a quarter of the Uranian year, equal to 84 Earth-years, the sun shines directly over each pole, leaving the other half of the planet to experience a long, dark, cold winter.

    The magnetic poles of most planets are typically lined up with the axis along which it rotates, but Uranus’ magnetic field is tilted, with its magnetic axis tipped over nearly 60 degrees from the planet’s axis of rotation. According to Norman F. Ness, et al, in an article in the journal Science, this leads to a strangely lopsided magnetic field for Uranus, with the strength of the field at the northern hemisphere’s surface being up to more than 10 times that of the strength at the southern hemisphere’s surface, affecting the formation of the auroras.

    Orbital characteristics

    Average distance from the sun: 1,783,939,400 miles (2,870,972,200 kilometers). By comparison: 19.191 times that of Earth

    Perihelion (closest approach to the sun): 1,699,800,000 miles (2,735,560,000 km). By comparison: 18.60 times that of Earth

    Aphelion (farthest distance from sun): 1,868,080,000 miles (3,006,390,000 km). By comparison: 19.76 times that of Earth
    The planet Uranus, seventh planet from the sun, is a giant ball of gas and liquid and was the first planet discovered with a telescope.

    ur
    Credit: Karl Tate, SPACE.com

    Composition & structure

    Atmospheric composition (by volume): 82.5 percent hydrogen, 15.2 percent helium, 2.3 percent methane

    Magnetic field: Magnetic pole tilt compared to rotational axis: 58.6 degrees

    Composition: The overall composition of Uranus is, by mass, thought to be about 25 percent rock, 60 to 70 percent ice, and 5 to 15 percent hydrogen and helium.

    Internal structure: Mantle of water, ammonia and methane ices; core of iron and magnesium-silicate
    Orbit & rotation

    Axial tilt: 97.77 degrees, compared to Earth’s 23.5 degrees

    Seasonal cycle & length: Approximately 21 years per season

    Orbital period: Approximately 84 Earth years
    Uranus’ climate

    The extreme axial tilt Uranus experiences can give rise to unusual weather. As sunlight reaches some areas for the first time in years, it heats up the atmosphere, triggering gigantic springtime storms roughly the size of North America, according to NASA.

    Ironically, when Voyager 2 first imaged Uranus in 1986 at the height of summer in its south, it saw a bland-looking sphere with only about 10 or so visible clouds, leading to it to be dubbed “the most boring planet,” writes astronomer Heidi Hammel in The Ice Giant Systems of Uranus and Neptune, a chapter in Solar System Update (Springer, 2007). It took decades later, when advanced telescopes such as Hubble came into play and the seasons changed, to see extreme weather on Uranus, where fast-moving winds can reach speeds of up to 560 miles (900 kilometers) per hour.

    NASA Voyager 2
    NASA/Voyager 2

    NASA Hubble Telescope
    NASA/ESA Hubble

    The rings of Uranus

    The rings of Uranus were the first to be seen after Saturn’s. They were a significant discovery, because it helped astronomers understand that rings are a common feature of planets, not merely a peculiarity of Saturn.

    Uranus possesses two sets of rings. The inner system of rings consists mostly of narrow, dark rings, while an outer system of two more-distant rings, discovered by the Hubble Space Telescope, are brightly colored, one red, one blue. Scientists have now identified 13 known rings around Uranus.
    Uranus’ moons

    Uranus has 27 known moons. Instead of being named after figures from Greek or Roman mythology, its first four moons were named after magical spirits in English literature, such as William Shakespeare’s “A Midsummer Night’s Dream” and Alexander Pope’s “The Rape of the Lock.” Since then, astronomers have continued this tradition, drawing names for the moons from the works of Shakespeare or Pope.

    Oberon and Titania are the largest Uranian moons, and were the first to be discovered, by Herschel in 1787. William Lassell, who was the first to see a moon orbiting Neptune, discovered the next two, Ariel and Umbriel. Then nearly a century passed before Miranda was found in 1948.

    Then, Voyager 2 visited the Uranian system in 1986 and found an additional 10, all just 16 to 96 miles (26-154 km) in diameter — Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida and Belinda — and each roughly made half of water ice and half of rock. Since then, astronomers using the Hubble Space Telescope and ground-based observatories have raised the total to 27 known moons, and spotting these was tricky — they are as little as 8 to 10 miles (12 to 16 km) across, blacker than asphalt, and nearly 3 billion miles (4.8 billion km) away.

    Between Cordelia, Ophelia and Miranda is a swarm of eight small satellites crowded together so tightly that astronomers don’t yet understand how the little moons have managed to avoid crashing into each other. Scientists suspect there might still be more moons, closer to Uranus than any known.

    In addition to moons, Uranus may also have a collection of Trojan asteroids — objects that share the same orbit as the planet — in a special region known as a Lagrangian point. The first was discovered in 2013, despite claims that the planet’s Langrangian point would be too unstable to host such bodies.

    Research & exploration

    NASA’s Voyager 2 was the first and as yet only spacecraft to visit Uranus. It discovered 10 previously unknown moons, and investigated its unusually tilted magnetic field.

    In 2013, the Planetary Science Decadal Survey recommended NASA consider a mission to the icy planet.

    See the full article here.

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  • richardmitnick 3:25 pm on November 20, 2014 Permalink | Reply
    Tags: , , , , NASA/ESA Hubble   

    From Hubble- Hubblecast 80: The Riddle of the Missing Stars 

    NASA Hubble Telescope

    Hubble

    New observations of four globular clusters in the Fornax dwarf galaxy have called into question one of the leading theories about how these clusters form. In this episode we explain the mystery behind these objects and how it is deepened by these new findings.

    f
    The Fornax dwarf galaxy is one of our Milky Way’s neighbouring dwarf galaxies. The Milky Way is, like all large galaxies, thought to have formed from smaller galaxies in the early days of the Universe. These small galaxies should also contain many very old stars, just as the Milky Way does, and a team of astronomers has now shown that this is indeed the case. This image was composed from data from the Digitized Sky Survey 2.

    Watch, enjoy, learn.

    See the full article here.

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  • richardmitnick 12:33 pm on November 20, 2014 Permalink | Reply
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    From Hubble: “The riddle of the missing stars” 

    NASA Hubble Telescope

    Hubble

    20 November 2014
    Søren Larsen
    Radboud University
    Nijmegen, Netherlands
    Tel: +31 (0)24 365 2806
    Email: s.larsen@astro.ru.nl

    Frank Grundahl
    Aarhus University
    Aarhus, Denmark
    Tel: +45 21 31 43 67
    Email: fgj@phys.au.dk

    Georgia Bladon
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Cell: +44 7816291261
    Email: gbladon@partner.eso.org

    Thanks to the NASA/ESA Hubble Space Telescope, some of the most mysterious cosmic residents have just become even more puzzling. New observations of globular clusters in a small galaxy show they are very similar to those found in the Milky Way, and so must have formed in a similar way. One of the leading theories on how these clusters form predicts that globular clusters should only be found nestled in among large quantities of old stars. But these old stars, though rife in the Milky Way, are not present in this small galaxy, and so, the mystery deepens.

    1
    Fornax_Dwarf Spheroidal Galaxy
    Image credit: NASA, ESA, S. Larsen (Radboud University, the Netherlands)

    Globular clusters — large balls of stars that orbit the centres of galaxies, but can lie very far from them — remain one of the biggest cosmic mysteries. They were once thought to consist of a single population of stars that all formed together. However, research has since shown that many of the Milky Way’s globular clusters had far more complex formation histories and are made up of at least two distinct populations of stars.

    Of these populations, around half the stars are a single generation of normal stars that were thought to form first, and the other half form a second generation of stars, which are polluted with different chemical elements. In particular, the polluted stars contain up to 50-100 times more nitrogen than the first generation of stars.

    The proportion of polluted stars found in the Milky Way’s globular clusters is much higher than astronomers expected, suggesting that a large chunk of the first generation star population is missing. A leading explanation for this is that the clusters once contained many more stars but a large fraction of the first generation stars were ejected from the cluster at some time in its past.

    This explanation makes sense for globular clusters in the Milky Way, where the ejected stars could easily hide among the many similar, old stars in the vast halo, but the new observations, which look at this type of cluster in a much smaller galaxy, call this theory into question.

    Astronomers used Hubble’s Wide Field Camera 3 (WFC3) to observe four globular clusters in a small nearby galaxy known as the Fornax Dwarf Spheroidal galaxy [1].

    NASA Hubble WFC3
    WFC3

    “We knew that the Milky Way’s clusters were more complex than was originally thought, and there are theories to explain why. But to really test our theories about how these clusters form we needed to know what happened in other environments,” says Søren Larsen of Radboud University in Nijmegen, the Netherlands, lead author of the new paper. “Before now we didn’t know whether globular clusters in smaller galaxies had multiple generations or not, but our observations show clearly that they do!”

    The astronomers’ detailed observations of the four Fornax clusters show that they also contain a second polluted population of stars [2] and indicate that not only did they form in a similar way to one another, their formation process is also similar to clusters in the Milky Way. Specifically, the astronomers used the Hubble observations to measure the amount of nitrogen in the cluster stars, and found that about half of the stars in each cluster are polluted at the same level that is seen in Milky Way’s globular clusters.

    This high proportion of polluted second generation stars means that the Fornax globular clusters’ formation should be covered by the same theory as those in the Milky Way.

    Based on the number of polluted stars in these clusters they would have to have been up to ten times more massive in the past, before kicking out huge numbers of their first generation stars and reducing to their current size. But, unlike the Milky Way, the galaxy that hosts these clusters doesn’t have enough old stars to account for the huge number that were supposedly banished from the clusters.

    “If these kicked-out stars were there, we would see them — but we don’t!” explains Frank Grundahl of Aarhus University in Denmark, co-author on the paper. “Our leading formation theory just can’t be right. There’s nowhere that Fornax could have hidden these ejected stars, so it appears that the clusters couldn’t have been so much larger in the past.”

    This finding means that a leading theory on how these mixed generation globular clusters formed cannot be correct and astronomers will have to think once more about how these mysterious objects, in the Milky Way and further afield, came to exist.

    The new work is detailed in a paper published today, 20 November 2014, in The Astrophysical Journal.
    Notes

    [1] The Milky Way’s gravity keeps Fornax orbiting around us as a satellite galaxy.

    [2] The clusters studied were named Fornax 1, 2, 3, and 5. Fornax 1, 3, and 5 are made up of approximately 40% first generation stars to 60% polluted second generation ones, while Fornax 2 contains around 60% first generation and 40% second generation.
    Notes for editors

    The international team of astronomers in this study consists of S. Larsen (Radboud University, the Netherlands), J. P Brodie (University of California, USA), F. Grundahl (Aarhus University, Denmark), and J. Strader (Michigan State University, USA).
    More information

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 5:21 am on November 20, 2014 Permalink | Reply
    Tags: , , , , Edwin Powell Hubble, NASA/ESA Hubble   

    From Hubble: “Today would be Edwin Hubble’s 120th birthday!” 

    NASA Hubble Telescope

    Hubble

    November 20, 2014
    No Writer Credit

    Edwin Powell Hubble – The man who discovered the cosmos

    eph
    Edwin Powell Hubble

    “I knew that even if I were second or third rate, it was astronomy that mattered.”

    This sentence, written by Edwin Hubble recalling his youth, tells us a lot about this stubborn, ambitious, sometimes even snobbish and arrogant young man. A man who eventually broke the promise made to his father and followed the path dictated by his passion.

    As a result of Hubble’s work, our perception of mankind’s place in the Universe has changed forever: humans have once again been set aside from the centre of the Universe. When scientists decided to name the Space Telescope after the founder of modern cosmology the choice could not have been more appropriate.

    A promising student

    Edwin Hubble was born in Missouri in 1889, the son of an insurance executive, and moved to Chicago nine years later. At his high school graduation in 1906, the principal said: “Edwin Hubble, I have watched you for four years and I have never seen you study for ten minutes.” He paused, leaving young Edwin on tenterhooks a moment longer, before continuing: “Here is a scholarship for the University of Chicago.”

    This high school scholarship was also awarded to another student by mistake, so the money had to be halved and Edwin had to supply the rest. He paid his expenses by tutoring, working in the summer and, in his junior year, by obtaining a scholarship in physics and working as a laboratory assistant. He finally obtained a degree in Mathematics and Astronomy in 1910.

    The Rhodes scholar

    A tall, powerfully built young man, Hubble loved basketball and boxing, and the combination of athletic prowess and academic ability earned him a Rhodes scholarship to Oxford. There, a promise made to his dying father, who never accepted Edwin’s infatuation for astronomy, led him to study law rather than science, although he also took up Literature and Spanish.

    He studied Roman and English Law at Oxford and returned to the United States only in 1913. Here he passed the bar examination and practised law half-heartedly for a year in Kentucky, where his family was then living.

    The beloved high school teacher and coach

    He was also hired by New Albany High School (New Albany, Indiana) in the autumn of 1913 to teach Spanish, Physics and Mathematics, and to coach basketball. His popularity as a teacher is recorded in the school yearbook dedicated to him: “To our beloved teacher of Spanish and Physics, who has been a loyal friend to us in our senior year, ever willing to cheer and help us both in school and on the field, we, the class of 1914, lovingly dedicate this book.”

    When the school term ended in May 1914, Hubble decided to pursue his first passion and so returned to university as a graduate student to study more astronomy.

    A new era for astronomy begins

    The famous British astrophysicist Stephen Hawking wrote in his book A Brief History of Time that Hubble’s “discovery that the Universe is expanding was one of the great intellectual revolutions of the 20th century.” Who could have guessed such a future for Edwin when he began his PhD in Astronomy at Chicago University in 1914?

    War postpones Hubble’s astronomical debut

    Early in 1917, while still finishing the work for his doctorate, Hubble was invited by George Ellery Hale, founder of the Mount Wilson Observatory., in Pasadena, California, to join the staff there. This was a great opportunity, but it came in April of a dreadful year. After sitting up all night to finish his PhD thesis and taking the oral examination the next morning, Hubble enlisted in the infantry and telegraphed Hale:”Regret cannot accept your invitation. Am off to the war.”

    He served in France and next returned to the United States in 1919. He went immediately to the Mount Wilson Observatory, where the newly discharged Major Hubble, as he invariably introduced himself, arrived, still in uniform, but ready to start observing.

    Hubble was lucky enough to be in the right place at the right time. Mount Wilson was the centre of observational work underpinning the new astrophysics, later called cosmology, and the 100-inch Hooker Telescope, then the most powerful on Earth, had just been completed and installed after nearly a decade of work.

    Mount Wilson 60 inchTelescope interior
    Hooker

    On the mountain Hubble encountered his greatest scientific rival, Harlow Shapley, who had already made his reputation by measuring the size of the Milky Way, our own Galaxy. Shapley had used a method pioneered by Henrietta Leavitt at the Harvard College Observatory that relied on the behaviour of standardised light variations from bright stars called Cepheid variables to establish the distance of an object.

    His result of 300 000 light-years for the width of the galaxy was roughly 10 times the previously accepted value. However Shapley, like most astronomers of the time, still thought that the Milky Way was all there was to the Universe. Despite a suggestion first made by William Herschel in the 18th century, he shared the accepted view that all nebulae were relatively nearby objects and merely patches of dust and gas in the sky.

    The turning point

    Hubble had to spend many bitterly cold nights sitting at the powerful Hooker telescope before he could prove Shapley wrong. In October 1923 he spotted what he first thought was a nova star flaring up dramatically in the M31 “nebula” in the constellation of Andromeda. After careful examination of photographic plates of the same area taken previously by other astronomers, including Shapley, he realised that it was a Cepheid star. Hubble used Shapley’s method to measure the distance to the new Cepheid. He could then place M31 a million light-years away – far outside the Milky Way and thus itself a galaxy containing millions of stars. The known Universe had expanded dramatically that day and – in a sense – the Cosmos itself had been discovered!

    m31
    M31 (Andromeda)
    The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. The image also shows Messier Objects 32 and 110, as well as NGC 206 (a bright star cloud in the Andromeda Galaxy) and the star Nu Andromedae. This image was taken using a hydrogen-alpha filter.
    18 September 2010
    Adam Evans

    Even The New York Times of the day realised the importance of the discovery: “Finds spiral nebulae are stellar systems. Doctor Hubbel [sic] confirms view that they are ‘island universes’ similar to our own.”

    Just the beginning

    This discovery was of great importance to the astronomical world, but Hubble’s greatest moment was yet to come. He began to classify all the known nebulae and to measure their velocities from the spectra of their emitted light. In 1929 he made another startling find – all galaxies seemed to be receding from us with velocities that increased in proportion to their distance from us – a relationship now known as Hubble’s Law.

    This discovery was a tremendous breakthrough for the astronomy of that time as it overturned the conventional view of a static Universe and showed that the Universe itself was expanding. More than a decade earlier, [Albert] Einstein himself had bowed to the observational wisdom of the day and corrected his equations, which had originally predicted an expanding Universe. Now Hubble had demonstrated that Einstein was right in the first place.

    The now elderly, world-famous physicist went specially to visit Hubble at Mount Wilson to express his gratitude. He called the original change of his beloved equations “the greatest blunder of my life.”

    Another war stops Hubble again

    Hubble worked on indefatigably at Mount Wilson until the summer of 1942, when he left to serve in World War II. He was awarded the Medal of Merit in 1946. Finally, he went back to his Observatory. His last great contribution to astronomy was a central role in the design and construction of the Hale 200-inch Telescope on Palomar Mountain. Four times as powerful as the Hooker, the Hale would be the largest telescope on Earth for decades. In 1949, he was honoured by being allowed the first use of the telescope.

    Caltech Palomar Hale Telescope
    Caltech Hale Telescope at Palomar interior
    Hale at Caltech/Palomar

    No Nobel Prize for an astronomer

    During his life, Hubble had tried to obtain the Nobel Prize, even hiring a publicity agent to promote his cause in the late 1940s, but all the effort was in vain as there was no category for astronomy. Hubble died in 1953 while preparing for several nights of observations, his last great ambition unfulfilled.

    He would have been thrilled had he known that the Space Telescope is named after him, so that astronomers can continue to “hope to find something we had not expected”, as he said in 1948 during a BBC broadcast in London.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 10:28 pm on November 18, 2014 Permalink | Reply
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    From Hubble: “A spiral in a furnace” 

    NASA Hubble Telescope

    Hubble

    This new Hubble image is a snapshot of NGC 986 — a barred spiral galaxy discovered in 1828 by James Dunlop. This close-up view of the galaxy was captured by Hubble’s Wide Field and Planetary Camera 2 (WFPC2).

    NASA Hubble WFPC2
    WFPC2

    986
    NGC 986
    Release date: 17 November 2014
    Hubble Space Telescope WFPC2

    NGC 986 is found in the constellation of Fornax (The Furnace), located in the southern sky. NGC 986 is a bright, 11th-magnitude galaxy sitting around 56 million light-years away, and its golden centre and barred swirling arms are clearly visible in this image.

    Barred spiral galaxies are spiral galaxies with a central bar-shaped structure composed of stars. NGC 986 has the characteristic S-shaped structure of this type of galactic morphology. Young blue stars can be seen dotted amongst the galaxy’s arms and the core of the galaxy is also aglow with star formation.

    To the top right of this image the stars appear a little fuzzy. This is because a gap in the Hubble data was filled in with data from ground-based telescopes. Although the view we see in this filled in patch is accurate, the resolution of the stars is no match for Hubble’s clear depiction of the spiral galaxy.

    See the full article here.

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  • richardmitnick 6:47 am on November 15, 2014 Permalink | Reply
    Tags: , , , , NASA/ESA Hubble   

    From Hubble: “The Party’s Over for These Youthful Compact Galaxies” 

    NASA Hubble Telescope

    Hubble

    November 13, 2014
    CONTACT

    Donna Weaver / Ray Villard
    Space Telescope Science Institute, Baltimore, Md.
    410-338-4493 / 410-338-4514
    dweaver@nasa.gov / villard@stsci.edu

    Paul Sell
    Texas Tech University, Lubbock, Texas
    806-742-7129
    paul.sell@ttu.edu

    Researchers using NASA’s Hubble Space Telescope and Chandra X-ray Observatory have uncovered young, massive, compact galaxies whose raucous star-making parties are ending early. The firestorm of star birth has blasted out most of the remaining gaseous fuel needed to make future generations of stars. Now the party’s over for these gas-starved galaxies, and they are on track to possibly becoming so-called “red and dead galaxies,” composed only of aging stars.

    NASA Chandra Telescope
    NASA Chandra schematic
    NASA/Chandra

    image
    Fast Evolution of a Galaxy
    This graphic illustrates how a vibrant, star-forming galaxy quickly transforms into a sedate galaxy composed of old stars. The scenario begins when two galaxies merge (Panel 1), funneling a large amount of gas into the central region. The gas compresses, sparking a firestorm of star birth, which blows out most of the remaining star-forming gas (Panel 2). Devoid of its fuel, the galaxy settles into a quiet existence, composed of aging stars.

    i2
    Outflows from 12 Merging Galaxies
    The 12 galaxies in these Hubble Space Telescope images are undergoing a firestorm of star birth, as shown by their bright white cores. Hubble reveals that the galaxies’ star-making frenzy was ignited by mergers with other galaxies. The odd shapes of many of the galaxies are telltale evidence of those close encounters.

    The new Hubble Wide Field Camera 3 observations suggest that energy from the star-birthing frenzy created powerful winds that are blowing out the gas, squelching future generations of stars. This activity occurred when the universe was half its current age of 13.7 billion years. The gas-poor galaxies may eventually become so-called “red and dead” galaxies, composed only of aging stars.

    NASA Hubble WFC3
    WFC3

    The galaxies are the most compact yet found. They contain as much mass as our Milky Way galaxy, but packed into a much smaller area. The smallest galaxies are about 650 light-years across.

    The Hubble false-color images were processed to bring out important details in the galaxies. The images were taken in 2010.

    Astronomers have debated for decades how massive galaxies rapidly evolve from active star-forming machines to star-starved graveyards. Previous observations of these galaxies reveal geysers of gas shooting into space at up to 2 million miles an hour. Astronomers have suspected that powerful monster black holes lurking at the centers of the galaxies triggered the gaseous outflows and shut down star birth by blowing out any remaining fuel.

    Now an analysis of 12 merging galaxies at the end of their star-birthing frenzy is showing that the stars themselves are turning out the lights on their own star-making party. This happened when the universe was half its current age of 13.7 billion years.

    “Before our study, the common belief was that stars cannot drive high-velocity outflows in galaxies; only more powerful supermassive black holes can do that,” explained Paul Sell of Texas Tech University in Lubbock, lead author of a science paper describing the study’s results. “Through our analysis we found that if you have a compact enough starburst, which Hubble showed was the case with these galaxies, you can actually produce the velocities of the outflows we observed from the stars alone without needing to invoke the black hole.”

    Team member Christy Tremonti of the University of Wisconsin-Madison first identified the galaxies from the Sloan Digital Sky Survey as post-starburst objects spouting high-speed gaseous fountains. The sharp visible-light views from Hubble’s Wide Field Camera 3 show that the outflows are arising from the most compact galaxies yet found. These galaxies contain as much mass as our Milky Way galaxy, but packed into a much smaller area. The smallest galaxies are about 650 light-years across.

    Sloan Digital Sky Survey Telescope
    Sloan Digital Sky Survey Telescope

    In such small regions of space, these galaxies are forming a few hundred suns a year. (By comparison, the Milky Way makes only about one sun a year.) This makes for a rowdy party that wears itself out quickly, in only a few tens of millions of years. One reason for the stellar shutdown is that the gas rapidly heats up, becoming too hot to contract under gravity to form new stars. Another possibility is that the star-birthing frenzy blasts out most of the star-making gas via powerful stellar winds.

    “The biggest surprise from Hubble was the realization that the newly formed stars were born so close together,” said team member Aleks Diamond-Stanic of the University of Wisconsin-Madison, who first suggested the possibility of starburst-driven outflows from these galaxies in a 2012 science paper. “The extreme physical conditions at the centers of these galaxies explain how they can expel gas at millions of miles per hour.”

    To identify the mechanism triggering the high-velocity outflows, Sell and his team used the Chandra X-ray Observatory and other telescopes to determine whether the galaxies’ supermassive black holes (weighing up to a billion suns) were the powerhouses driving them. After analyzing all of the observations, the team concluded that the black holes were not the source of the outflows. Rather, it was the powerful stellar winds from the most massive and short-lived stars at the end of their lives, combined with their explosive deaths as supernovae.

    Based on their analysis of the Hubble and Chandra data, team members suggest that the “party begins” when two gas-rich galaxies collide, funneling a torrent of cold gas into the merging galaxies’ compact center. The large amount of gas compressed into the small space ignites the birth of numerous stars. The energy from the stellar firestorm then blows out the leftover gas, quenching further star formation.

    “If you stop the flow of cold gas to form stars, that’s it,” explained Sell, who conducted the research while a graduate student at the University of Wisconsin-Madison. “The stars stop forming, and the galaxy rapidly evolves and may eventually become a red, dead elliptical galaxy. These extreme starbursts are quite rare, however, so they may not grow into the typical giant elliptical galaxies seen in our nearby galactic neighborhood. They may, instead, be more compact.”

    The team’s results were published in the July 11 edition of the Monthly Notices of the Royal Astronomical Society.

    See the full article here.

    Please help promote STEM in your local schools.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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    • Kopernik 10:25 am on November 17, 2014 Permalink | Reply

      You all, like me, tend to pursue a singular line of investigation without much attention to peripheral activities of the studied subject. But then, otherwise one would be drifting off in many other possible interesting directions. Still, when you use phrases like ‘the party’s over’ and ‘red and dead’ to describe a galaxy’s future, that is a little too near sighted. There is always a second act, and most likely many more.

      In the case of young galaxies churning out multiple stars in a short time such as to use up their supply of gases and over heat what is left, and even blow that out of reach – that is just the first phase towards the development of a grand galaxy.

      Hypothesis: ‘Young’ galaxies contrive to ensure their long term prospects by dispatching at a high velocity high density objects (in most cases black holes) to beyond the present star zone into those outer reaches rich in molecular hydrogen and dark matter. There at some distance these eventually become the nuclei of satellite and dwarf galaxies. After amassing some quantity of stars, hydrogen, and dark matter these progeny galaxies are recalled to the progenitor galaxy where they must surrender their cache of ‘goodies’ to the maternal galaxy.

      The dynamic nature of the massive compact galaxies you describe are ideal for producing interactions between those many bodies that would cause some to be ejected from that galaxy.
      You cannot of course agree with this scenario. Still, scientists should be open to new avenues of exploration. k

      Like

  • richardmitnick 9:37 am on November 14, 2014 Permalink | Reply
    Tags: , , , , , NASA/ESA Hubble   

    From Hubble: “Hubblecast 79: Q&A with Dr J part 2″ 

    NASA Hubble Telescope

    Hubble

    In the summer of 2014 we asked the public to send us their Hubble- and astronomy-related questions, and the response was incredible! In this episode Dr J answers a selection of the questions about science related to Hubble. These range from questions about what Hubble has achieved within the Solar System, to the science it has uncovered at the very edge of the observable Universe. In this episode Dr J explains some of the key concepts, and biggest misconceptions, about the Universe we live in.

    Watxh, enjoy, learn.

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition
    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 12:37 pm on November 11, 2014 Permalink | Reply
    Tags: , , , , NASA/ESA Hubble   

    From Hubble: NGC 5584 

    NASA Hubble Telescope

    Hubble

    This view from the NASA/ESA Hubble Space Telescope shows the beautiful spiral galaxy NGC 5584. This galaxy has played a key role in a new study that measures the expansion rate of the Universe to greater accuracy than ever before.

    5584

    NGC 5584 was first spotted as a faint glow in the constellation of Virgo by the great visual observer E. E. Barnard, back in 1881, using just a 12.5-cm telescope.

    But, by bringing the power of Hubble to bear, the galaxy can be resolved into thousands of separate stars.

    Some of these stars vary in brightness and are classified as Cepheids. These are brilliant pulsating stars with a remarkable property — once the time it takes a Cepheid to brighten and fade is known, then it is possible to find how bright it actually is. When this information is combined with a measurement of how bright the star appears it is easy to work out how far away the star actually lies. This method is the most accurate and effective way to measure the distances to most nearby galaxies.

    This trick has now been used as part of a major new study of the expansion rate of the Universe, led by Adam Riess at the Space Telescope Science Institute in Baltimore. By studying many Cepheids in several galaxies the team has been able to refine our knowledge of this expansion rate, expressed as a number known as Hubble’s constant, to an accuracy of 3.3 percent.

    In addition to many Cepheids NGC 5584 was also recently the site of a type Ia supernova. These dramatic explosions of white dwarf stars are used as reference beacons for mapping the expansion, and acceleration, of the more remote Universe so this galaxy is a very valuable link between the two distance scales.

    This picture was created from many exposures taken with Hubble’s Wide Field [Camera] 3. Images through three filters have been combined to create this composite picture. Light detected through a filter that transmits most visible light (F350LP) is coloured white, light coming through a yellow/green filter (F555W) is coloured blue and near infrared light (the F814W filter) is coloured red. The field of view 2.4 arcminutes across and the total exposure time was 20.8 hours.

    Credit:

    NASA, ESA, A. Riess (STScI/JHU), L. Macri (Texas A & M University), and the Hubble Heritage Team (STScI/AURA)

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 8:50 am on November 7, 2014 Permalink | Reply
    Tags: , , , , NASA/ESA Hubble   

    From Hubble: “Hubble Surveys Debris-Strewn Exoplanetary Construction Yards” 

    NASA Hubble Telescope

    Hubble

    November 6, 2014
    Ray Villard
    Space Telescope Science Institute, Baltimore, Md.
    410-338-4514
    villard@stsci.edu

    Glenn Schneider
    University of Arizona, Tucson, Ariz.
    520-621-5865
    gschneider@as.arizona.edu

    Astronomers using NASA’s Hubble Space Telescope have completed the largest and most sensitive visible-light imaging survey of dusty debris disks around other stars. These dusty disks, likely created by collisions between leftover objects from planet formation, were imaged around stars as young as 10 million years old and as mature as more than 1 billion years old.

    six
    This is a set of images from a NASA Hubble Space Telescope survey of the architecture of debris systems around young stars. Ten previously discovered circumstellar debris systems, plus MP Mus (a mature protoplanetary disk of age comparable to the youngest of the debris disks), were studied. Hubble’s sharp view uncovers an unexpected diversity and complexity in the structures. The disk-like structures are vast, many times larger than the planetary distribution in our solar system. Some disks are tilted edge-on to our view, others nearly face-on. Asymmetries and warping in the disks might be caused by the host star’s passage though interstellar space. Alternatively, the disks may be affected by the action of unseen planets. In particular, the asymmetry in HD 181327 looks like a spray of material that is very distant from its host star. It might be the aftermath of a collision between two small bodies, suggesting that the unseen planetary system may be chaotic. The stars surveyed may be as young as 10 million years old and as mature as more than 1 billion years old. The visible-light survey was done with the Space Telescope Imaging Spectrograph (STIS). The STIS coronagraph blocks out the light from the host star so that the very faint reflected light from the dust structures can be seen. The images have been artificially colored to enhance detail.

    Object Names: HD 15115, HD 32297, HD 61005, HD 181327, MP Mus

    stis

    “It’s like looking back in time to see the kinds of destructive events that once routinely happened in our solar system after the planets formed,” said survey leader Glenn Schneider of the University of Arizona’s Steward Observatory. The survey’s results appeared in the Oct. 1, 2014, issue of The Astronomical Journal.

    Once thought to be simply pancake-like structures, the unexpected diversity and complexity of these dusty debris structures strongly suggest they are being gravitationally affected by unseen planets orbiting the star. Alternatively, these effects could result from the stars’ passing through interstellar space.

    The researchers discovered that no two “disks” of material surrounding stars look the same. “We find that the systems are not simply flat with uniform surfaces,” Schneider said. “These are actually pretty complicated three-dimensional debris systems, often with embedded smaller structures. Some of the substructures could be signposts of unseen planets.” The astronomers used Hubble’s Space Telescope Imaging Spectrograph to study 10 previously discovered circumstellar debris systems, plus MP Mus, a mature protoplanetary disk of age comparable to the youngest of the debris disks.

    Irregularities observed in one ring-like system in particular, around a star called HD 181327, resemble the ejection of a huge spray of debris into the outer part of the system from the recent collision of two bodies.

    “This spray of material is fairly distant from its host star — roughly twice the distance that Pluto is from the Sun,” said co-investigator Christopher Stark of NASA’s Goddard Space Flight Center, Greenbelt, Maryland. “Catastrophically destroying an object that massive at such a large distance is difficult to explain, and it should be very rare. If we are in fact seeing the recent aftermath of a massive collision, the unseen planetary system may be quite chaotic.”

    Another interpretation for the irregularities is that the disk has been mysteriously warped by the star’s passage through interstellar space, directly interacting with unseen interstellar material. “Either way, the answer is exciting,” Schneider said. “Our team is currently analyzing follow-up observations that will help reveal the true cause of the irregularity.”

    Over the past few years astronomers have found an incredible diversity in the architecture of exoplanetary systems -— planets are arranged in orbits that are markedly different than found in our solar system. “We are now seeing a similar diversity in the architecture of accompanying debris systems,” Schneider said. “How are the planets affecting the disks, and how are the disks affecting the planets? There is some sort of interdependence between a planet and the accompanying debris that might affect the evolution of these exoplanetary debris systems.”

    From this small sample, the most important message to take away is one of diversity, Schneider said. He added that astronomers really need to understand the internal and external influences on these systems, such as stellar winds and interactions with clouds of interstellar material, and how they are influenced by the mass and age of the parent star, and the abundance of heavier elements needed to build planets.

    Though astronomers have found nearly 4,000 exoplanet candidates since 1995, mostly by indirect detection methods, only about two dozen light-scattering, circumstellar debris systems have been imaged over that same time period. That’s because the disks are typically 100,000 times fainter than, and often very close to, their bright parent stars. The majority have been seen because of Hubble’s ability to perform high-contrast imaging, in which the overwhelming light from the star is blocked to reveal the faint disk that surrounds the star.

    The new imaging survey also yields insight into how our solar system formed and evolved 4.6 billion years ago. In particular, the suspected planet collision seen in the disk around HD 181327 may be similar to how the Earth-Moon system formed, as well as the Pluto-Charon system over 4 billion years ago. In those cases, collisions between planet-sized bodies cast debris that then coalesced into a companion moon.

    See the full article here.

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 3:28 pm on November 6, 2014 Permalink | Reply
    Tags: , , , , NASA/ESA Hubble   

    From Hubble: “Jets, bubbles, and bursts of light in Taurus” 

    NASA Hubble Telescope

    Hubble

    6 November 2014
    Georgia Bladon
    ESA/Hubble Public Information Officer
    Garching, Germany
    Tel: +49-89-3200-6855
    Email: gbladon@partner.eso.org

    The NASA/ESA Hubble Space Telescope has snapped a striking view of a multiple star system called XZ Tauri, its neighbour HL Tauri, and several nearby young stellar objects. XZ Tauri is blowing a hot bubble of gas into the surrounding space, which is filled with bright and beautiful clumps that are emitting strong winds and jets. These objects illuminate the region, creating a truly dramatic scene.

    gig

    xl

    This dark and ominous landscape is located some 450 light-years away in the constellation of Taurus (The Bull). It lies in the north-eastern part of a large, dark cloud known as LDN 1551.

    Just to the left of centre in this image, embedded within a rust-coloured cloud, lies XZ Tauri. While it appears to be a single star, this bright spot actually consists of several stars. It has long been known to be a binary, but one of these two stars is thought also to be a binary, making a total of three stars within a single system.

    This is not the first time that Hubble has observed XZ Tauri — between the years of 1995 and 2000, a hot bubble of gas was spotted expanding outwards from the system. This bubble can be seen as the small orange lobe very close to the top left of XZ Tauri. This gas is speeding out from the star system, leaving a trail spanning tens of billions of kilometres. As the bubble travels it hits slower moving material, triggering pulses of light and rippling shockwaves.

    Above and to the right of XZ Tauri, an equally epic scene is unfolding. Wisps of deep red seem to be streaking away from the blue-tinged clumps on the right. This bright blue patch contains a star known as HL Tauri [1], which is associated with Herbig-Haro object HH 150. Herbig-Haro objects are streaks of hot gas blasted into space by newborn and newly forming stars and LDN 1551 is particularly rich in these dramatic objects.

    In the bottom right of this Hubble image is another Herbig-Haro object known as HH 30 (opo9905), associated with the variable star V1213 Tauri. The star itself is hidden within a flat, bright disc of dust that is split in half by a dark lane. This dust blocks direct light from V1213 Tauri, but the star is visible via its reflected light and the prominent, knotty jets it is blasting out into space.

    Hubble previously viewed HH 30, alongside XZ Tauri, with its Wide Field Planetary Camera 2 between the years of 1995 and 2000. The observations were used to image and study the changes in disc brightness and jet strength over the five-year period. V1213 Tauri’s strong magnetic field forms the jets by funnelling and shepherding gas from the disc, accelerating it along the star’s magnetic poles to form two narrow beams.

    NASA Hubble WFPC2
    WFPC2 (decomissioned)

    A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt, and won third prize.

    In a press release issued by the European Southern Observatory today observations from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal extraordinarily fine and never-before-seen detail in the planet-forming disc around HL Tauri. The new observations are an enormous step forward in the observation of how protoplanetary discs develop and how planets form.

    ALMA Array
    ALMA Array
    Notes

    [1] XZ Tauri and HL Tauri are textbook examples of a class of stars known as T Tauris — young and rapidly rotating, with strong magnetic fields and powerful winds. They have yet to reach the temperatures necessary for hydrogen fusion deep in their cores. It will take around 100 million years for these stars to trigger these reactions and evolve into fully-fledged stars like the Sun.

    See the full article here.

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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